Osoriellus indescriptus, Irmler, 2014

Irmler, Ulrich, 2014, The Neotropical species of the genus Osoriellus FAGEL, 1959 (Coleoptera: Staphylinidae: Osoriinae), Beiträge Zur Entomologie = Contributions to Entomology 64 (2), pp. 231-354 : 272-273

Osoriellus indescriptus n. sp.

( Figs 44 A-C, 94B)

Type material: Holotype, male: USA, Bahamas: South Bimini Island , 1.4.1952, leg. E. Mayr ( AMNH).

Paratypes: USA, Bahamas: 30 specimens with same data as holotype ; 99 specimens, 1.5.1951, leg. C. Crazier; 17 specimens 1.6.1951, leg. C. Crazier ; 5 specimens, 1.7.1951, leg. P. Vaurio ; 11 specimens, 1.8.1951, leg. P. Vaurio ( ANHM, UIC); Andros Island, Middenhair Coppice , 2.1 mi S, 0.7 mi E Staniard Creek, low interior coppice litter , 1 specimen, 6.05.1994, R. Anderson ( AMNH); Church’s Blue Hole , 1.7 mi E Love Hill, high interior coppice litter , 4 specimens, 26.04.1994, leg. R. Anderson ( KNHM) ; London Ridge , 2.7 mi N, 0.8 mi E Forfar F. Stn., high interior coppice litter, 1 specimen, 06.05.1994, leg. R. Anderson ( KNHM).

Diagnosis: The species is closely related to O. exiguus . Both species cannot be shurely identified without dissection of the aedeagus. On average, O. indescriptus is more slender and slightly darker than O. exiguus and the punctation of the pronotum is slightly deeper and denser. However, the species can be easily separated by the shape of the aedeagus. The apical lobe of O. exiguus is slender and smoothly curved, whereas it is thick and triangular in O. indescriptus .

Description: Length: 2.5 mm long. Colouration: Light brown; head darker brown; elytra, legs and antennae yellow; posterior margin of elytra dark.

Head: 0.42 mm long, 0.50 mm wide; eyes not prominent; slightly shorter than temples; sides of fore-head deeply emarginate; sides of clypeus nearly parallel; apical edge of clypeus even; without granules at angles; setiferous punctation deep and dense; interstices between punctures less than half as wide as diameter of punctures; small area at base of antennae and midline on vertex impunctate; without microsculpture; surface polished and shiny.

Antennae as long as head; second antennomere globular and thick; thicker than three following antennomeres; triangular third antennomere shorter and smaller than second; fourth antennomere as wide as third, but shorter and wider than long; following antennomeres increasing in width; fifth to eighth antennomeres wider than long; nineth and tenth antennomeres nearly quadrate.

Pronotum: 0.57 mm long, 0.51 mm wide; widest at anterior angles; evenly convergent to rounded posterior angles; setiferous punctation deep and dense; still denser and deeper than on head; interstices between punctures less than half as wide as diameter of punctures; narrow midline impunctate; without microsculpture; surface polished and shiny.

Elytra: 0.56 mm long, 0.50 mm wide; with weak coriaceous ground-sculpture; setiferous punctation fine and less deep than on pronotum and head.

Abdomen with large setiferous punctation; nearly as deep and dense as on pronotum; narrow midline on posterior tergites impunctate.

Protibia: 0.27 mm long, 0.08 mm wide; with 8 spines at outer edge; WLR: 3.0; comb at inner edge visible throughout its total length; posterior face with few yellow setae.

Aedeagus with short, thick and triangular apical lobe; nearly as thick as basal lobe; inner edge of apical lobe without sensillae.

Etymology: The specific name is a combination of the epithet in and the Latin word describere meaning not described. The name refers to the confusion between this species and O. exiguus during my studies.

Figures

Fig. 43-47: Osoriellus-s. str.-group: O. exiguus (43), Osoriellus indescriptus (44), O. coruscus (45), O. luteus (46); O. punctatellus (47); antenna (A), protibia (B), aedeagus in lateral aspect (C); scale bar: 0.1 mm.